Gas turbine engines generally include a combustor with a number of fuel nozzles positioned about an end cap assembly in various configurations. For example, several gas turbine combustion system offered by General Electric Corporation of Schenectady, N.Y. provide a six (6) fuel nozzle configuration with a center or a secondary fuel nozzle surrounded by five (5) outer or primary fuel nozzles extending from the end cap assembly. Such combustion systems generally mix together one or more fuel streams and air streams before entry of the mixed stream into a reaction or a combustion zone. Such fuel/air premixing tends to reduce overall combustion temperatures as well as undesirable emissions such as nitrogen oxides (NOx) and the like. Similar types of fuel nozzle/end cap assembly designs for combustors and the like are known.
As is known, fuel nozzles generally include a number of fuel and air tubes mounted onto a flange. The fuel nozzles may be positioned within the end cap assembly in a somewhat cantilevered fashion. The fuel nozzles may be positioned within the end cap assembly via a number of floating collars. The floating collars generally fit over the outside surface of the fuel nozzle burner tubes. The floating collars provide function as air seals. The floating collars, however, may experience significant wear during operation. Specifically, the collars may rotate during use so as to cause friction between the collars and the end cap assembly. Replacement and durability of the floating seals thus are common design issues.
There is a desire therefore for an improved seal between the fuel nozzles and the end cap assembly. The seals should improve the durability of the overall combustor in a low cost but reliable fashion.